The invention relates to preparing compositions useful as electrolytes for alkali metal polymer batteries and the electrochemical cells and batteries made with such electrolytes.
Alkali metal polymer batteries generally include a positive electrode, a negative electrode, and an electrolyte positioned between the electrodes. The electrolyte can act to separate the electrodes and, because it is ionically conductive, provides a path through which ions flow from one electrode to the other during charging and discharging of the cell. Electrolytes can be solid or liquid. Liquid electrolytes include aqueous and nonaqueous solutions and molten salts. Solid electrolytes include ionically conducting polymers. Electrolytes can include salts, and liquids or polymers or combinations thereof capable of solvating the salt.
Lithium polymer batteries that include a lithium metal negative electrode, a metal oxide positive electrode and a solid electrolyte offer the advantage of high energy storage capacity and rechargeability. To optimize the cycle number or cycle life of a battery or cell, it is desirable to minimize or eliminate the growth of dendrites. Dendrite growth can result from the nonuniform plating of lithium onto the negative electrode during the charging step. Dendrites can puncture the electrolyte and make contact with the opposite electrode, thus causing an internal short circuit in the cell, which can compromise cell performance and shorten its useful life.